/**
 * Copyright 2007 Jason Horman, Pete Aykroyd
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.functor;

import org.apache.commons.collections.map.LRUMap;

public class FunctorCache {
	public static class LRU<ParamType, ReturnType> extends UnaryFunction<ParamType, ReturnType> {
		private UnaryFunction<ParamType, ReturnType> function;
		private LRUMap cache;

		public LRU(UnaryFunction<ParamType,ReturnType> function, int lruSize) {
			this.function = function;
			cache = new LRUMap(lruSize);
		}

		public ReturnType evaluate(ParamType p) {
			ReturnType result = (ReturnType) cache.get(p);
			if (result == null) {
				result = function.evaluate(p);
				cache.put(p, result);
			}

			return result;
		}
	}
}
